A conventional cellular network is deployed as a homogenous network of macrocell base stations. The macrocell base stations may all have similar antenna patterns and similar high-level transmit powers. To accommodate increases in data traffic, more macrocell base stations can be deployed in a homogenous network, but such a solution is often unattractive due to increased inter-cell interference on the downlink and due to the high costs associated with site acquisition for newly deployed macrocell base stations.
Because of these drawbacks, cellular network operators are turning to heterogeneous networks to meet the demands of increased data traffic. In heterogeneous networks, small cell base stations are used to provide small coverage areas that overlap with the comparatively larger coverage areas provided by macrocell base stations. The small coverage areas are specifically provided in areas with high data traffic (or so called hotspots) to increase capacity. Examples of small cell base stations include, in order of decreasing coverage area, microcell base stations, picocell base stations, and femtocell base stations or home base stations.
One problem with heterogeneous networks is that the addition of small cell base stations can lead to the cellular network being overprovisioned in terms of data traffic capacity during times when traffic is low. For example, during certain periods of time, many of the deployed small cell base stations may actually be serving no traffic or such a little amount of traffic that a macrocell base station can handle the traffic while still meeting quality of service (QoS) requirements. In these instances, the small cell base stations are consuming power that could otherwise be conserved. Because power costs contribute to a large percentage of the overall operational costs of running a cellular network, it would be beneficial to turn-off the small cell base stations (or at least portions of the small cell base stations) when they have little or no traffic load. In addition, it would be beneficial to turn-off the small cell base stations (or at least portions of the small cell base stations) when they have little or no traffic load to reduce downlink interference caused by these devices.
The embodiments of the present disclosure will be described with reference to the accompanying drawings. The drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.